The screenwriter behind Marvel's Doctor Strange has suggested that a Tibetan character in the film has been written as Celtic to 'avoid offending China'.

C Robert Cargill told the Daily Telegraph that The Ancient One, who appears as an Asian man in the Marvel comics, will be played as a Celtic woman by Tilda Swinton in the movie.

He suggested that there was a risk that the film, which also stars Benedict Cumberbatch as Doctor Strange, could be banned in China if the Government thought 'you decided to get political'.

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Mr Cargill told the Telegraph: "The Ancient One originates from Tibet, so if you acknowledge that Tibet is a place and that he's Tibetain, you risk alienating one billion people."

Ms Swinton's casting as The Ancient One caused controversy when it was announced, with critics accusing the American studio of 'whitewashing'.

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The Ancient One character is a Tibetan High Lama who mentors the surgeon turned sorcerer in the movie, which was shot in Nepal.

However, Mr Cargill said the decision to write the character as a woman aimed to 'mitigate stereotypes'.

Earlier this month, Ms Swinton said that there were 'very great reasons' for the changes that had been made to the comic for the film.

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She told Digital Spy: "The script that I was presented with did not feature an Asian man for me to play, so that was never a question when I was being asked to do it.

"There are very great reasons for us to feel very settled and confident with the decisions that were made."

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In a statement, Marvel confirmed that the Ancient One character has been written as a Celt for the film.

The film will be released on October 28.